Stretching from deep in the Atlantic Ocean to the central African country's inland hills, Congo's Conkouati-Douli National Park is home to a host of rare and endangered species including leatherback turtles, mandrills, gorillas and chimpanzees.

The U.S.-based Wildlife Conservation Society (WCS) says oil exploration by Zetah, a subsidiary of French oil company Maurel & Prom, is damaging the park's habitat and says the Brazzaville government should never have granted exploration rights because the law creating the park prohibits it.

"Zetah oil company is causing serious environmental damage, increased poaching pressures, and general disturbance through terrestrial oil exploration activities," Paul Elkan, director of the WCS programme in Congo, told Reuters late on Thursday.

Elkan said seismic explosions -- carried out to help geologists plot the likely location of oil reserves beneath rock -- were being carried out in ecologically sensitive areas.

In addition, new roads, tracks and bridges made it easier for poachers to get in and out of the park, and animal snares had been found around tented camps erected for oil workers within the park, he said.

Zetah had failed to carry out the usual environmental impact assessments required before exploration work even outside a national park, Elkan said, adding: "There is a simple violation of legal process which has taken place."

GOVERNMENT, FIRM DENY ABUSE

The August 1999 decree creating the national park, a copy of which was seen by Reuters, forbids oil exploration and other rights within the park, but Forestry and Environment Minister Henri Djombo insisted the environment was being safeguarded.

"It is true that the Congolese state has granted an oil exploration permit to Zetah. But from that to say that they are destroying the environment is overdramatic ... the park is managed according to conservation norms," Djombo said.

Maurel & Prom also denied its subsidiary's activities were harming the park.

"No explosives are being used at the surface, everything is underground, and supervised by the (Congolese) army," a spokesman for Maurel & Prom, Laurent Wormser, said in Paris.

"Maurel & Prom is very careful about the environment," Wormser said. "We are not new to Africa. We work with perfect transparency with everyone. ... We will respect everything the Congolese authorities want us to do. ... We condemn poaching."

WCS said a concerted joint effort with Congolese authorities had all but halted the trade in poached "bush meat" from Conkouati-Douli in 2005.

But after oil exploration work began last August, Elkan said the number of animals confiscated at one control post had more than trebled to 350 in October, numbering 54 protected species including two dead gorillas and one chimpanzee.

The Congo river basin, spanning Congo, the larger Democratic Republic of Congo and several other countries, is home to a host of endangered species, many of them found in Conkouati-Douli.

"It's the highest diversity area in Congo," Elkan said. "It has tremendous ecotourism potential because of the proximity of the ocean." (Additional reporting by Alistair Thomson in Dakar)